The present invention relates to a tractor protection function. It finds particular application in conjunction with delivering pneumatic fluid from a tractor to a trailer based on a trailer park brake pressure and will be described with particular reference thereto. It will be appreciated, however, that the invention is also amenable to other applications.
Current trailer control strategies involve using a relay valve to apply full system air pressure to a supply port of an antilock braking system (ABS) modulator. The ABS modulator is set to hold off pressure, and pulses to send a set volume of air into the trailer control line to apply trailer brakes. There is no mechanism to compensate for any loss of air volume in the trailer and/or verify that the required air pressure has been delivered to the trailer.
The present invention provides a new and improved apparatus and method for compensating for any loss of air volume in the trailer and/or verifying that the required air pressure has been delivered to the trailer.